Endoscope having pipe connection structure and producing method thereof

ABSTRACT

An endoscope having a pipe connection structure includes a pipe of a corrosion-resistant alloy material and a piping block of a corrosion-resistant alloy material, the piping block having a pipe insertion hole. An end of the pipe is fitted in the pipe insertion hole, the pipe and the piping block are connected by welding by irradiating a laser beam on the entire circumference of an area where the end of the pipe is fitted in the pipe insertion hole in the piping block, and an axial length of the pipe inserted in the pipe insertion hole is in a range of 0.5 to 2 times a wall thickness of the pipe.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.12/354,910, filed Jan. 16, 2009, which claims the benefit of JapanesePatent Application No. 2008-008627, filed on Jan. 18, 2008. The entiredisclosure of each of the above-identified applications, including thespecification, drawings, and claims, is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates to a pipe connection structure of anendoscope and a producing method thereof.

Related Art

Generally, pipe connection structures in endoscopes configured such thatone end of a pipe made of a corrosion-resistant alloy material is fittedin a pipe insertion hole which is formed in a piping block made of acorrosion-resistant alloy material and fixed. Then, the pipe and thepiping block are welded by irradiating a laser beam on the entirecircumference of the exterior edge of their inter-fit area. An exampleof such a technique is disclosed, in Japanese Published ExaminedApplication No. HEI 4-25007.

In a pipe and a piping block, their respective metals are melted at thelaser beam-irradiated portion and a portion in the close vicinitythereof, whereby they are connected integrally. In the inter-fit area ofthe pipe and the piping block, an opposite side of the melted portionmay not be welded and a gap may be left between the portions where thepipe and the piping block.

SUMMARY OF THE INVENTION

At the pipe connection structure of an endoscope, the pipe passagecommunicates with the inside of human body during endoscopicinvestigation. Therefore, if there is a gap in the portion behind theinter-fit area between the pipe and the piping block, filthy liquid maybe collected thereat, which may become a source of infection. However,if the inter-fit length is too short, sufficient connection strengthcannot be achieved. Further, a leakage of liquid from the inter-fit areais not allowed.

Aspects of the present invention provide a pipe connection structure ofan endoscope and a producing method thereof in which a pipe and a pipingblock can be connected and fixed with sufficient strength and no leakageby laser welding without causing pooling of filthy liquid.

Means for Solving the Problem

According to aspects of the invention, there is provided a pipeconnection structure for an endoscope, which is provided with a pipemade of a corrosion-resistant alloy material, and a piping block made ofa corrosion-resistant alloy material, the piping block having a pipeinsertion hole. An end of the pipe is fitted in the pipe insertion holeand the pipe and the piping block are connected by welding byirradiating a laser beam on the entire circumference of an area wherethe end of the pipe is fitted in the hole formed on the piping block. Anaxial length of the pipe inserted in the pipe insertion hole is in arange of 0.5 to 2 times a wall thickness of the pipe.

According to aspects of the invention, there is provided a method ofproducing a pipe connection structure for an endoscope, comprising astep of preparing a pipe made of a corrosion-resistant alloy material, astep of preparing a piping block made of a corrosion-resistant alloymaterial, the piping block having a pipe insertion hole, a step offitting an end of the pipe in the pipe insertion hole, and a step ofconnecting the pipe and the piping block by welding by irradiating alaser beam on the entire circumference of an area where the end of thepipe is fitted in the hole formed on the piping block, an axial lengthof the pipe inserted in the pipe insertion hole is in a range of 0.5 to2 times a wall thickness of the pipe.

According to aspects of the present invention, the pipe and the pipingblock can be securely connected with sufficient strength by laserwelding without causing collection of filthy liquid and leak of liquid.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is an enlarged cross sectional side view of a pipe connectionstructure of an endoscope according to an embodiment of the invention.

FIG. 2 is an enlarged cross sectional side view of the pipe connectionstructure of the endoscope in a pre-connection state, according to theembodiment of the invention.

FIG. 3 is a cross sectional side view of the pipe connection structureof the endoscope according to the embodiment of the invention.

FIG. 4 is a cross sectional side view of the pipe connection structurewith a rod-shaped member being inserted for the laser irradiation,according to an embodiment of the invention.

FIG. 5 is a cross sectional side view of a pipe connection structurewhen the inner surface of the pipe connection structure is finished,according to the embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, referring to accompanying drawings, embodiments of thepresent invention will be described.

FIG. 3 shows a pipe connection structure which forms a suction pipe-lineand the like in an endoscope. An example of an endoscope having a pipeconnection structure, to which the embodiments of the invention areapplicable, is U.S. Pat. No. 5,840,015, teachings of which areincorporated herein by reference. In the example shown in FIG. 3, oneend of a pipe 1 for allowing fluid to pass through is connected with apiping block 2 and fixed thereto. The piping block 2 is formed in theshape of a hollow cylinder with one end side is closed. Each of the pipe1 and the piping block 2 is a hollow cylindrical member made of acorrosion-resistant alloy material such as stainless steel (e.g., SUS304).

FIG. 1 shows an enlarged view of the area where the pipe 1 and thepiping block 2 are connected, and FIG. 2 shows the pipe 1 and the pipingblock 2 before they are connected. In the piping block 2, acommunicating hole 3 is formed. The communication hole 3 hassubstantially the same inner diameter size as that of the pipe 1.

A pipe insertion hole 4 having an inner diameter which is sized to fitwith the end of the pipe 1 and is formed to have a diameter slightlylarger than the inner diameter of the communicating hole 3. The pipeinsertion hole 4 is formed to have a shoulder to which the end surfaceof the pipe 1 is contacted. The piping block 2 is further provided witha clearance hole 5 which is formed to be a large diameter on the surfacefrom which the pipe 1 is inserted. The communicating hole 3, the pipeinsertion hole 4 and the clearance hole 5 are formed coaxially, and arearranged along the central axis of the coaxially provided holes. Thepipe insertion hole 4 is formed such that the pipe 1 tightly fits in thepipe insertion hole 4 without loosening (e.g., an outer diameter of thepipe 1 plus 0.05 mm or less).

The depth d of the pipe insertion hole 4 (i.e., an inter-fit lengthalong the axis of the pipe 1 with respect to the insert hole 4) issubstantially equal to the wall thickness t of the pipe 1. That is, d˜t,in FIG. 1.

As shown in FIG. 1, a laser beam R is emitted from outside toward theentire circumference of the exterior edge of the inter-fit area when oneend of the pipe 1 is fitted in the pipe insertion hole 4. With thisprocess, the pipe 1 and the piping block 2 are securely connected bywelding (seam welding). In FIG. 1, the portion indicated by a numeral 6is the welded area where the pipe 1 and piping block 2 are fused andintegrally connected.

The laser beam R is emitted from outside toward the entire circumferenceof the exterior edge of the inter-fit area of the pipe 1 and the pipeinsertion hole 4 at an angle of 5 to 60 degrees (i.e., 5°≦θ≦60°) withrespect to the axis of the end side of the pipe 1.

When the irradiation angle θ is smaller than 5 degrees or larger than 60degrees, it becomes difficult to accurately irradiate with the laserbeam R on the exterior edge of the inter-fit area of the pipe 1 and thepipe insertion hole 4. Incidentally, a YAG laser is used as the laserbeam R, for example.

When the pipe 1 and the piping block 2 are welded according to the abovemanner, since the inter-fit length d of the pipe 1 with respect to theinsert hole 4 is substantially the same as the wall thickness t of thepipe 1, the inter-fit area is included in the welded area 6, and no gapis left in the inter-fit area.

Therefore, the pipe 1 and the piping block 2 can be connected withsufficient strength without causing collection of filthy liquid andleakage thereof. Moreover, the welding can be completed in a very shorttime, for example, approximately in ten seconds.

It should be noted that, when the inter-fit length d of the pipe 1 isapproximately no more than 2 times the wall thickness t of the pipe 1,the inter-fit area is wholly included in the welded area 6, and no gapis left. When the inter-fit length d is approximately at least 0.5 timesthe wall thickness t, sufficient welding strength can be achieved.Therefore, the inter-fit length d along the axis of the pipe 1 withrespect to the insert hole 4 may be in the range of 0.5 to 2 times thewall thickness t of the pipe 1.

FIG. 4 shows a condition where a solid or a hollow rod-shaped (i.e.,cylindrical) member 10 made of a material such as copper, which isinfusible by the laser beam R of a YAG laser is fitted in the pipe 1 andthe piping block 2 during the irradiation with laser beam R forconnecting the pipe 1 and the piping block 2.

The rod-shaped member 10 is inserted from the outside and is fitted inthe pipe 1 at a position corresponding to the area irradiated with thelaser beam R. With the rod-shaped member 10, irradiation of the laserbeam R to portions which should not be or are unnecessary to beirradiated can be prevented.

Further, each internal wall surface of the pipe 1 and the piping block 2can be prevented from being finished as a rough uneven state.Incidentally, the rod-shaped member 10 may be made of gold or silver,however, the costs will be increased.

Optionally, when the laser beam R irradiation process has been finished,as shown in FIG. 5, the internal wall surface of the welded area 6 ofthe pipe 1 and the piping block 2 which have been roughened by the laserbeam R irradiation may be finished to be a smooth surface with polishingusing a micro grindstone 11 and the like.

According to the above-described embodiment, the pipe 1 is fitted in theinsert hole 4 formed on the piping block 2 for temporarily fixing theconnection therebetween. At this stage, the end of the pipe 1 is abuttedagainst the bottom surface of the insert hole 4. Then, by appropriatelyadjusting the welding depth of the laser beam R, the fitted potions ofthe pipe 1 and piping block 2, and the bottom of the insert hole 4against which the end of the pipe 1 is abut are welded. Since theconnected portions are completely molten and then connected integrally,no interspace is formed therebetween.

The present disclosure relates to the subject matters contained inJapanese Patent Applications No. 2008-008627, filed on Jan. 18, 2008,and No. 2008-239029, filed on Sep. 18, 2008, which are expresslyincorporated herein by reference in their entireties.

What is claimed is:
 1. An endoscope having a pipe connection structure,comprising: a pipe of a corrosion-resistant alloy material; and a pipingblock of a corrosion-resistant alloy material, the piping block having apipe insertion hole, wherein an end of the pipe is fitted in the pipeinsertion hole, the pipe and the piping block are connected by weldingby irradiating a laser beam on the entire circumference of an area wherethe end of the pipe is fitted in the pipe insertion hole in the pipingblock, an axial length of the pipe inserted in the pipe insertion holeis in a range of 0.5 to 2 times a wall thickness of the pipe.
 2. Theendoscope having a pipe connection structure according to claim 1,wherein the axial length of the pipe inserted in the pipe insertion holeis substantially the same as the wall thickness of the pipe.
 3. Theendoscope having a pipe connection structure according to claim 1,wherein the piping block has a communication hole which communicateswith the inside of the pipe, the pipe insertion hole and thecommunication hole being arranged next to each other, the pipe insertionhole having a larger diameter than the communication hole so that a stepis provided between the pipe insertion hole and the communication hole,an end side surface of the pipe contacting the step provided between thepipe insertion hole and the communication hole.
 4. A method of producingan endoscope having a pipe connection structure, comprising: preparing apipe of a corrosion-resistant alloy material; preparing a piping blockof a corrosion-resistant alloy material, the piping block having a pipeinsertion hole; fitting an end of the pipe in the pipe insertion hole;and connecting the pipe and the piping block by welding by irradiating alaser beam on the entire circumference of an area where the end of thepipe is fitted in the pipe insertion hole in the piping block, an axiallength of the pipe inserted in the pipe insertion hole is in a range of0.5 to 2 times a wall thickness of the pipe.
 5. The method according toclaim 4, wherein the axial length of the pipe inserted in the pipeinsertion hole is substantially the same as the wall thickness of thepipe.
 6. The method according to claim 4, further comprising inserting arod-shaped member of a material infusible by the laser beam across theinside of the pipe and inside of the communication hole during theirradiation of the laser beam for welding.
 7. The method according toclaim 6, wherein the laser beam is a YAG laser.
 8. The method accordingto claim 6, wherein the rod-shaped member is copper.